1. Field of the Invention
The present invention relates to an autonomous mobile device which plans a travel route and autonomously travels along the travel route.
2. Description of the Related Art
A conventional autonomous mobile device autonomously travels in an ambient environment. In order for an autonomous mobile device to autonomously travel in the ambient environment, an environmental map showing an area with objects (obstacles) and an area without objects within the travel space is required. Various methods have been proposed as the method of acquiring this kind of environmental map. Here, Japanese Patent Application Laid-open No. H10-143243 discloses technology for representing the ambient environment as a map using a landmark. With this technology, for example, if a mobile area is an office, the landmark is set at positions where the autonomous mobile robot is able to pass through such as corners and branching points of a hallway, center of the room, entrance and exits of doors to and from rooms, and so on. Meanwhile, SLAM (Simultaneous Localization and Mapping) is known as technology for estimating a self-location and creating the environmental map, in real time, while traveling. Here, Japanese Patent Application Laid-open No. H7-129238 discloses a mobile robot which uses SLAM to generate a topographic map (environmental map) based on topographic data obtained as a result of measuring distances using a laser range finder (or a camera).
In the technology of creating an environmental map using landmarks described in the Japanese Patent Application Laid-open No. H10-143243, there is considerable burden on the user for setting the landmarks and performing other operations, and much time and effort (work, man-hours) are required to create the environmental map. Meanwhile, in the method of creating the environmental map by using SLAM, for example, when attempting to set setting points (for instance, starting point, target pass-through point, goal point) on an environmental map which was prepared in advance, there is a possibility that such setting points will be displaced in comparison to their actual positions. Thus, there may be cases where it is necessary to match the setting points with the actual environment.
Moreover, the following problems have been indicated in the method of creating an environmental map by using SLAM.
1. There are cases where an inconsistency arises in the created environmental map due to the accumulation of measurement errors. In particular, there are cases where the start portion and the end portion do not coincide upon creating a circular environmental map (so-called circular route problem).
2. When the layout of the mobile area is partially changed, it is necessary to recreate the entire environmental map.